The use of hinges for the opening and closing of various apparatus is notoriously well known. Torque hinges are a subset of hinges that allow an apparatus to have resistance throughout the apparatus' entire range of motion.
In electronic markets, torque hinges have been utilized in a number of areas. One example is the notebook computer. Torque hinges are desirable because a user wishes to open the computer and use the top lid portion as a computer display. Because users all differ in height and in location during use of the computer, it is desirable to be able to open the lid of the computer and hold the lid of the computer at various angles to maximize a users' visibility, avoid a glare, etc. A torque hinge provides constant resistance throughout the computer lid's range of motion and is therefore ideal for this application.
A conventional, prior art spring torque hinge 10 is illustrated in FIG. 1. A spring 12 is wound around a shaft 14. Spring 12 has two ends 12a and 12b that are connected to a clasp 16 that holds the compression of spring 12 fixed. Spring torque hinge 10 has what is referred to as an interference fit. An interference fit comprises two articles; one designed to fit within the other. The article that is to fit within the other is designed to be slightly larger than the opening of the other article. For example, with spring torque hinge 10 the inside diameter of spring 12 is slightly smaller than the outside diameter of shaft 14 such that when spring 12 is wrapped around shaft 14 the "interference" between spring 12 and shaft 14 causes the necessary friction for continuous resistance through shaft's 14 range of movement.
Spring torque hinge 10 suffers from a serious problem. Over time, spring 12 loses its original "tightness", or uniformity, and begins to assume the diameter of shaft 14. This is undesirable since this results in decreased friction between spring 12 and shaft 14. Therefore, the desired resistance, or torque, is not maintained over time. Testing of a standard torque hinge (10,000 actuations) resulted in spring torque hinge 10 losing more than 50% of its initial torque.
It is an object of this invention to provide a new hinge that provides improved wear over time, improved frictional characteristics, increased life, and decreased cost. Other objects and advantages of the invention will be apparent to those of ordinary skill in the art having reference to the following specification and drawings.